MPG jump after recall

[Markus]

Hi everyone, I was so excited I joined the forum to spread the news!

I just got the recall work done for my 2009 Aveo 5 LT.

Pre recall work - mileage was about 27 to 28, no better.

After the recall work - my mileage has shot up to 35.9 (no air) and 35.2 (air). NOT BAD.

I always liked my car, but now I downright LOVE it!

Wonder if anyone else experienced this after the recall was done?

I'm suspecting cracked plugs were there from day one.

Mark

[dahanger]

Wow! I wish that happened after my recall parts were installed. Mine is still the plain old 25-27.

[Chevy Customer Svc]

Hi everyone, I was so excited I joined the forum to spread the news!

I just got the recall work done for my 2009 Aveo 5 LT.

Pre recall work - mileage was about 27 to 28, no better.

After the recall work - my mileage has shot up to 35.9 (no air) and 35.2 (air). NOT BAD.

I always liked my car, but now I downright LOVE it!

Wonder if anyone else experienced this after the recall was done?

I'm suspecting cracked plugs were there from day one.

Mark

Hi Markus,

That's great to hear you had such an improvement in MPG. Keep me posted if anything changes.

Vanessa
GM Customer Service

[vettekid12]

y is our fuel mileage so poor for such a small car/small engine?

[Thymeclock]

y is our fuel mileage so poor for such a small car/small engine?

You may find this thread informative (click here).

[HeavyDuty]

I had similar mileage to Markus but winter was low 20's. Markus do you have the 09 LT or LS ? a/c and p/s with auto ? Maybe a sunroof ? I happened upon something here but I am still testing it out. There are people whom are getting some MPG and there are people who are getting none..needs to be a common connection. My 2009 has a 95 amp alternator and A/C and P/S which is being run by a tiny micro-belt. This belt is over 60 bucks up here ( and I can only buy it from one place other than GM Auto stores here are telling me they will never be stocking or able to order that belt) any other serpentine belt is 30....so it's double and darn hard to come by. There are several breaks in the serial numbers of the Aveo in 2009...small changes can sometimes make a very big impact. I am looking at the parts from the 2009 that have been carried over to the Sonic such as the coil, camshaft position sensors and seeing what's been changed. What's been changed is a great place to start looking for trouble.

[HeavyDuty]

Here is the question of the day....could a poor/defective serpentine belt tensioner on an under designed belt drive system produce a sound or vibration that would cause the knock sensor to instruct the ECM to make adjustments that would in turn reduce MPG and power.....and other things, LOL I do believe I know the answer to this question already.

Rabbit...?
Though engine knocks happen fast in an engine cycle, they can still be prevented. One way of doing so is by ensuring that your engine’s knock sensor is working—that is, if your car has one. Most cars nowadays have one installed in their engine. But that doesn’t mean that car owners know they have one in their vehicle. Many car owners only realize their car has a knock sensor when their engine is already knocking.
So if you don’t know where yours is located in your engine, the picture on the right might give you an idea. In most cars, the knock sensor is bolted onto the center of the cylinder block’s wall, approximately at the level of the cylinders. But there are also some vehicles where it is bolted onto the cylinder head. Well, these differences in location are actually due to differences in estimates of where the knock sensor would work most effectively—meaning, where it would be most sensitive to engine knocks.



A knock sensor uses piezo electric mechanism

Most knock sensors look like a midget spark plug with most of its bulk in its center; it has a threaded part on one end and a small pin or pole-like projection on the other. Other knock sensor designs don’t have the threaded part, which is used to bolt the sensor to the block; instead, they have a threaded bolt hole.
When knocks occur inside a cylinder, the sensor picks up the reverberations, which have frequencies ranging from 6 to 8 kiloHertz. Inside the knock sensor, a resonating plate relays the shock waves to a piezo electric crystalline element. This element then generates a small amount of voltage. In turn, this weak electric signal goes to the vehicle’s electronic control unit and tells it to retard or delay the firing of the spark in the combustion chamber. That way there wouldn’t be two flame fronts igniting simultaneously in the cylinders and thus, knock wouldn’t occur.
Unfortunately, the knock sensor can handle only mild engine knocks. It sometimes happens that the knock frequency is way beyond the frequency range the sensor is designed to pick up, so it’s either the sensor would detect it too late or it would not detect the knock at all. But then that’s in extreme cases. So long as you take good care of your engine and ensure that it has a perfectly working knock sensor in place, you really don’t have to worry much about extreme-case engine knocks.

[wfernanddez7404]

I had the recall done on my 2010 LT and did not notice any improvement in MPG

[odypilots]

I had the recall done on my 2010 LT and did not notice any improvement in MPG

If the recalled parts on your car weren't defective, it wouldn't change the mileage. I'm not sure what percentage of the recalled parts were actually defective.